Imaging device

ABSTRACT

A imaging device includes: a case having bottom and top plate portions with an accommodation space interposed therebetween; a dome cover protruding outward from the case through an opening formed in the top plate portion; an annular support member allowing a circumferential edge portion of the dome cover to be interposed between the support member and the top plate portion; a lens unit; and an elastic member disposed between the bottom plate portion and the lens unit and allows the lens unit to be biased in a direction toward the dome cover. The lens unit includes an outer circumferential portion disposed on outside of a lens in a direction along the bottom plate portion and engaged with an inside opening of the support member, and a stepped portion provided in the outer circumferential portion and restricts movement in the direction approaching the dome cover by abutting the support member.

BACKGROUND

1. Technical Field

This disclosure relates to a imaging device.

2. Description of the Related Art

As a imaging device having impact resistance, for example, a monitoringcamera device disclosed in Japanese Patent Unexamined Publication No.2012-60445 is known. In the monitoring camera device, as illustrated inFIG. 16, exterior unit 501 with a dome cover is fixed to fixing pedestalportion 503 by mounting screw 505 and covers an internal structureincluding lens unit 507. Lens unit 507 is supported by a pair of lensunit support portions 509. Lens unit support portions 509 are pivoted ata pair of support portions 513 of base portion 511. Fixing pedestalportion 503 fixes and supports base portion 511 and mounting board 515.A capturing element included in lens unit 507 is connected to mountingboard 515 via transmission cable 517. Spring accommodation portion 519of lens unit support portion 509 is fitted to protrusion 521 of lensunit 507. Protrusion 521 of lens unit 507 is pressed by elastic member523. In a case where a predetermined impact is applied to the dome coverin the monitoring camera device, lens unit 507 is pressed in an oppositedirection of the direction of a subject. As a result, lens unit 507performs a retreat operation.

In the monitoring camera device disclosed in Japanese Patent UnexaminedPublication No. 2012-60445, the lens unit is fixed to the fixingpedestal. Therefore, various components including the fixing pedestalare interposed between the dome cover and a lens. Therefore, positionaldeviations in the components and the like act as a cumulative tolerance,and it is difficult to ensure the positional accuracy of the dome coverand the lens. Particularly, as the capturing element has a higher pixelcount, the positional relationship between the dome cover and the lensaffects image quality.

SUMMARY

This disclosure has been made taking the foregoing circumstances intoconsideration, and provides a imaging device which realizes high imagequality by increasing the positional accuracy of a dome cover and alens.

A imaging device of this disclosure includes a case, a dome cover, anannular support member, a lens unit which includes a lens, and anelastic member. The case includes a bottom plate portion and a top plateportion with an accommodation space interposed therebetween. The domecover protrudes outward from the case through an opening formed in thetop plate portion of the case. The support member allows acircumferential edge portion of the dome cover to be interposed betweenthe support member and the top plate portion. The elastic member isdisposed between the bottom plate portion of the case and the lens unitand allows the lens unit to be biased in a direction approaching thedome cover. The lens unit includes an outer circumferential portion anda stepped portion. The outer circumferential portion is disposed onoutside of the lens in a direction along the bottom plate portion of thecase and is engaged with an inside opening of the support member. Thestepped portion is provided in the outer circumferential portion andrestricts movement in the direction approaching the dome cover byabutting the support member.

According to this disclosure, high image quality can be realized byincreasing the positional accuracy of the dome cover and the lens.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a imaging deviceviewed from a dome cover side in an exemplary embodiment;

FIG. 2 is an exploded perspective view illustrating an example of theimaging device in the exemplary embodiment;

FIG. 3 is a perspective view illustrating an example of a lower case onwhich a lens unit is mounted in the exemplary embodiment;

FIG. 4A is a perspective view illustrating an example of the lower casein the exemplary embodiment, FIG. 4B is a perspective view illustratingan example of the lower case on which a lens holder is mounted in theexemplary embodiment, FIG. 4C is a perspective view illustrating anexample of the lower case on which a lens holding spring is mounted inthe exemplary embodiment, and FIG. 4D is a perspective view illustratingan example of the lower case on which the lens unit is mounted in theexemplary embodiment;

FIG. 5 is an exploded perspective view illustrating an example of a lensunit holding structure in the exemplary embodiment;

FIG. 6A is an exploded perspective view illustrating an example of thelens unit and the lens holder in the exemplary embodiment, and FIG. 6Bis a sectional view illustrating an example of the lens holder and thelens unit in an assembled state in the exemplary embodiment;

FIG. 7 is an exploded perspective view illustrating an example of anupper case in the exemplary embodiment;

FIG. 8A is a perspective view illustrating an example of the upper casein the exemplary embodiment, FIG. 8B is a perspective view illustratingan example of the upper case on which a dome packing is mounted in theexemplary embodiment, FIG. 8C is a perspective view illustrating anexample of the upper case on which a dome cover is mounted in theexemplary embodiment, FIG. 8D is a perspective view illustrating anexample of the upper case on which an inner dome is mounted in theexemplary embodiment, FIG. 8E is a perspective view illustrating anexample of the upper case on which a dome bracket is mounted in theexemplary embodiment, and FIG. 8F is a perspective view illustrating anexample of the upper case on which a sub-cover packing is mounted in theexemplary embodiment;

FIG. 9A is a perspective view illustrating an example of an adjustinggear unit in the exemplary embodiment, and FIG. 9B is a perspective viewillustrating an example of the upper case on which the adjusting gearunit is mounted in the exemplary embodiment;

FIG. 10 is a perspective view illustrating an example of a state inwhich the lens unit and the adjusting gear unit mesh with each other inthe exemplary embodiment;

FIG. 11A is an exploded perspective view illustrating an example of thedome bracket and the lens unit in the exemplary embodiment, and FIG. 11Bis a perspective view illustrating an example of the lens unit in astate of abutting the dome bracket in the exemplary embodiment;

FIG. 12A is a plan view illustrating an example of the dome bracketabutted by the lens unit in the exemplary embodiment, and FIG. 12B is aside view of FIG. 12A;

FIG. 13 is a sectional view taken along line 13-13 of FIG. 12B;

FIG. 14A is a perspective view illustrating an example of the imagingdevice from which a sub-cover is detached in the exemplary embodiment,and FIG. 14B is an enlarged view illustrating an example of the vicinityof a blocking portion provided in the sub-cover in the exemplaryembodiment;

FIG. 15A is a plan view illustrating an example of a rotation structureof the lens unit of the imaging device in the exemplary embodiment, andFIG. 15B is an enlarged view illustrating main parts of the vicinity ofan adjusting gear illustrated in FIG. 15A; and

FIG. 16 is an exploded perspective view illustrating a imaging deviceaccording to the related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an exemplary embodiment of this disclosure will bedescribed with reference to the drawings.

FIG. 1 is a perspective view illustrating an example of a imaging deviceviewed from a dome cover side in an exemplary embodiment. FIG. 2 is anexploded perspective view illustrating an example of imaging device 11.FIG. 3 is a perspective view illustrating an example of lower case 15 onwhich lens unit 13 is mounted.

Imaging device 11 is, for example, mounted on the ceiling or wall as amonitoring camera device. Imaging device 11 has a positioning structureand an adjusting gear structure. The positioning structure includes case17, dome cover 19, dome bracket 21 (see FIG. 7) (an example of a supportmember), lens unit 13, and lens holding spring 23 (see FIG. 4C) (anexample of an elastic member). The adjusting gear structure includescase 17, lens unit 13, sub-cover 25, and adjusting gear unit 27.

Case 17 includes bottom plate portion 31 and top plate portion 33 withaccommodation space 29 interposed therebetween. Case 17 includes lowercase 15 (an example of a first case) having bottom plate portion 31 andupper case 35 (an example of a second case) having top plate portion 33.Lower case 15 and upper case 35 are joined to each other.

Lower case 15 is formed, for example, in a cylindrical shape with a flatbottom. Electric wire lead-out space 37 is provided as a cut-out from aportion of lower case 15 in the circumferential direction thereof.Connection electric wire 39 is disposed in electric wire lead-out space37. Lens unit 13 is mounted in the center portion of lower case 15. Inaddition, in lower case 15, for example, various electronic components(not illustrated) and a board (not illustrated) having the electroniccomponents mounted thereon and having a shape that surrounds lens unit13 are mounted.

Connection electric wire 39 supplies power, for example, to electroniccomponents in imaging device 11 such as lens unit 13 and transmitvarious signals from the electronic components in imaging device 11 suchas lens unit 13. Connection electric wire 39 is disposed so that aportion thereof extends to the inside of lower case 15 (notillustrated).

Upper case 35 is formed, for example, in a flat cylindrical shape inwhich the apex of a conical portion has opening 41. Upper case 35 ismounted coaxially with lower case 15 to cover lower case 15. Dome cover19 which protrudes outward from case 17 through opening 41 formed in topplate portion 33 is mounted on upper case 35.

FIGS. 4A to 4D are perspective views illustrating an example of aprocess in which various components of lower case 15 are mounted. Thecomponents are mounted in order of FIGS. 4A, 4B, 4C, and 4D. FIG. 4A isa perspective view illustrating an example of lower case 15. FIG. 4B isa perspective view illustrating an example of lower case 15 on whichlens holder 43 is mounted. FIG. 4C is a perspective view illustrating anexample of lower case 15 on which lens holding spring 23 is mounted.FIG. 4D is a perspective view illustrating an example of lower case 15on which lens unit 13 is mounted.

FIG. 5 is an exploded perspective view illustrating an example of a lensunit holding structure. FIG. 6A is a perspective view illustrating anexample of a state in which lens unit 13 and lens holder 43 aredisassembled from each other. FIG. 6B is a sectional view illustratingan example of a state in which lens holder 43 and lens unit 13 areassembled to each other.

In imaging device 11, lens holder 43 is fixed to top plate portion 31.Lens unit 13 is held to be movable in a direction approaching and awayfrom dome cover 19 by lens holder 43 and lens holding spring 23. Asillustrated in FIG. 4A, lens holder mounting portion 45 is formed at thecenter portion of lower case 15.

As illustrated in FIG. 4B, lens holder 43 is fixed to lens holdermounting portion 45 by holder fixing screw 47 illustrated in FIG. 5.Lens holder 43 is formed, for example, in a cylindrical shape. Aplurality of locking flange portions 49 which protrude outward in theradial direction are provided in the upper end portion of lens holder 43in the circumferential direction thereof. As illustrated in FIG. 4C,lens holding spring 23 is disposed on the outside of lens holder 43.

As illustrated in FIGS. 6A and 6B, lens unit 13 has, for example,cylindrical fixing base portion 53 in the bottom portion on the oppositeside of lens 51. A plurality of inside locking pieces 55 (an example ofan engagement member) which protrude inward in the radial direction areprovided in the lower end (the end on the bottom plate portion 31 side)of fixing base portion 53 in the circumferential direction thereof.

Fitting outer diameter portion 57 which has a constant radius from itsaxis is formed in the outer periphery of lens unit 13. Spring seat 59having a smaller diameter than that of fitting outer diameter portion 57is formed in the outer periphery of lens unit 13 on the opposite side oflens 51. One end side of lens holding spring 23 abuts spring seat 59.The other end side of lens holding spring 23 of which one end side abutsspring seat 59 abuts lens holder mounting portion 45.

As illustrated in FIG. 4D, as lens unit 13 presses lens holding spring23 from above, the outside of lens holder 43 is inserted into fixingbase portion 53. When fixing base portion 53 rotates about its axis,inside locking pieces 55 are locked to recess portions 61 (an example ofan engagement portion) of locking flange portions 49 illustrated in FIG.6A. Accordingly, lens unit 13 is in a state of being held in lens holder43 even by the biasing force of lens holding spring 23 without beingseparated from lens holder 43.

In this state, that is, in the state in which lens unit 13 is held inlens holder 43, when lens unit 13 is pressed against the lens holderside, lens unit 13 can retreat while compressing lens holding spring 23.The retreat distance becomes, for example, stroke S illustrated in FIG.6B to absorb an impact on lens unit 13.

As described above, lens holding spring 23 is disposed between bottomplate portion 31 and lens unit 13 and allows lens unit 13 to be biasedin a direction approaching dome cover 19. Since lens unit 13 is lockedto recess portions 61 of locking flange portions 49 with the biasingforce, the position of lens unit 13 is fixed on the bottom plate portion31 side of lower case 15 during the assembly of upper case 35 and lowercase 15, resulting in the facilitation of the assembly. Lens holdingspring 23 is, for example, a coil spring disposed coaxially with lensunit 13.

Lens unit 13 includes stepped portion 69 illustrated in FIG. 6B on thelens 51 side of fitting outer diameter portion 57. Stepped portion 69abuts the circumferential edge of inside opening 65 of dome bracket 21(see FIG. 13).

When upper case 35 is assembled to lower case 15, dome bracket 21 abutsstepped portion 69 of lens unit 13 to restrict the movement of lens unit13 in a direction approaching dome cover 19, and presses lens unit 13against the restoring force of lens holding spring 23. Inside lockingpieces 55 of fixing base portion 53 are pressed, and locking thereof torecess portions 61 of locking flange portions 49 is released. Whenlocking to recess portions 61 of locking flange portions 49 is released,lens unit 13 is able to rotate around locking flange portions 49.

Lens unit 13 includes capturing element 63, is disposed in accommodationspace 29, and is rotatable about its optical axis. Fitting outerdiameter portion 57 is rotatably fitted into inside opening 65 of domebracket 21 (see FIG. 13). Segment gear 67 which has a larger outsidediameter than that of fitting outer diameter portion 57 is formed in theouter circumferential portion of lens unit 13. Segment gear 67 mesheswith adjusting gear unit 27 (see FIG. 9A), which will be describedlater.

As fitting outer diameter portion 57 is fitted into inside opening 65 ofdome bracket 21, the position of lens unit 13 is determined to have thesame axis as that of dome cover 19. In a state in which stepped portion69 abuts dome bracket 21, segment gear 67 is disposed in accommodationspace 29.

In lens unit 13, lens fixing member 71 (see FIG. 13) which holds lens 51is, for example, mounted to be movable with respect to unit body 75 viafloating mount 73. Floating mount 73 allows lens fixing member 71 to bebiased in a direction to float on unit body 75 by floating spring 77.Lens unit 13 includes, for example, a fisheye lens as lens 51 and thusfunctions as an omnidirectional camera. Therefore, even in a case whereimaging device 11 captures images in all directions (360 degrees),panning and tilting are unnecessary.

FIG. 7 is an exploded perspective view illustrating an example of uppercase 35.

In upper case 35, dome packing 79, dome cover 19, inner dome 81, anddome bracket 21 are mounted by dome cover fixing screws 83. Adjustinggear unit 27 is mounted on the accommodation space 29 side of upper case35 by adjusting gear fixing screws 85. Sub-cover 25 is detachablymounted to a portion of the outside of upper case 35 by sub-cover fixingscrews 87.

Dome cover 19 includes, for example, hemispherical dome portion 89, anddome cover flange portion 91 which protrudes outward in the radialdirection from the circumferential edge of the opening side of domeportion 89. Dome cover 19 is formed as a portion of lens 51, and theoptical path thereof is designed to be integrated with that of lens 51.Specifically, the ratio (Tmax−Tmin)/r of the difference (Tmax−Tmin)between the maximum thickness Tmax and the minimum thickness Tmin ofdome cover 19 to the radius r of dome cover 19 is 0.75% or higher and 6%or lower. Dome cover 19 is formed of, for example, polycarbonate (PC).Dome cover 19 may use, for example, refraction of light through uneventhickness in the relationship between dome cover 19 and lens 51 (seeFIG. 5) to enhance the quality of a captured image.

Inner dome 81 includes annular inner dome flange portion 93. Domebracket 21 is formed as an annular plate which overlaps dome coverflange portion 91 and inner dome flange portion 93 to be pressed andfixed. In the outer circumferential edges of dome cover flange portion91, inner dome flange portion 93, and dome bracket 21, a plurality of(for example, four) screw insertion portions 95 through which dome coverfixing screws 83 pass are formed in the circumferential direction.

FIGS. 8A to 8F are perspective views illustrating an example of aprocess in which various components of upper case 35 are mounted. Thecomponents are mounted in order of FIGS. 8A, 8B, 8C, 8D, 8E, and 8F.

FIG. 8A is a perspective view illustrating an example of upper case 35.FIG. 8B is a perspective view illustrating an example of upper case 35on which dome packing 79 is mounted. FIG. 8C is a perspective viewillustrating an example of upper case 35 on which dome cover 19 ismounted. FIG. 8D is a perspective view illustrating an example of uppercase 35 on which inner dome 81 is mounted. FIG. 8E is a perspective viewillustrating an example of upper case 35 on which dome bracket 21 ismounted. FIG. 8F is a perspective view illustrating an example of uppercase 35 on which sub-cover packing 97 is mounted.

The assembly of upper case 35 is performed, for example, by disposingupper case 35 so that accommodation space 29 is positioned on the upperside as illustrated in FIG. 8A. As illustrated in FIG. 8B, dome packing79 is disposed on packing seating surface 99 provided in thecircumferential edge of opening 41 of upper case 35.

As illustrated in FIG. 8C, dome portion 89 of dome cover 19 is insertedinto opening 41 around which dome packing 79 is disposed. Dome cover 19is disposed so that screw insertion portions 95 of dome cover flangeportion 91 are aligned with screw fixing portions 101 of upper case 35.Dome cover flange portion 91 of dome cover 19 abuts dome packing 79.Accordingly, a gap between opening 41 and dome cover flange portion 91is air-tightly sealed by dome packing 79.

As illustrated in FIG. 8D, inner dome 81 is disposed on the inside ofdome cover 19. Screw insertion portions 95 of inner dome flange portion93 in inner dome 81 are disposed to be aligned with screw fixingportions 101.

As illustrated in FIG. 8E, dome bracket 21 is disposed to overlap innerdome flange portion 93. Dome cover fixing screws 83 inserted throughscrew insertion portions 95 of dome bracket 21 are fixed to screw fixingportions 101 of upper case 35. Dome bracket 21 allows thecircumferential edge portion (dome cover flange portion 91) of domecover 19 to be interposed between inner dome 81 and top plate portion33. Accordingly, in the circumferential edge of opening 41 of upper case35, dome packing 79, inner dome 81, and dome bracket 21 are fixed in astacked state.

As illustrated in FIG. 8F, sub-cover packing 97 is mounted on adjustinggear penetration portion 103 (an example of a penetration hole) of uppercase 35.

As described above, in imaging device 11, dome cover 19, dome bracket21, and the like are provided in upper case 35 while lens unit 13, lensholding spring 23, and the like are provided in lower case 15. Aftereach of upper case 35 and lower case 15 is assembled in advance(pre-assembled), upper case 35 and lower case 15 are finally assembledinto one body as imaging device 11. Therefore, upper case 35 and lowercase 15 can be easily assembled.

Next, adjusting gear unit 27 will be described.

FIG. 9A is a perspective view illustrating an example of adjusting gearunit 27. FIG. 9B is a perspective view illustrating an example of uppercase 35 on which adjusting gear unit 27 is mounted. FIG. 10 is aperspective view illustrating an example of a state in which lens unit13 and adjusting gear unit 27 mesh with each other.

Adjusting gear unit 27 is fixed to upper case 35 by adjusting gearfixing screws 85. Adjusting gear unit 27 can be assembled to adjustinggear holder 105 in a state in which intermediate gear 107 and adjustinggear 109 mesh with each other. Substantially the half of adjusting gear109 in the axial direction thereof meshes with intermediate gear 107.That is, a portion of adjusting gear 109 which does not mesh withintermediate gear 107 protrudes in a direction in which the portionfloats from intermediate gear 107. The protruding portion of adjustinggear 109 is exposed to the outside of upper case 35 from adjusting gearpenetration portion 103. Adjusting gear 109 is formed coaxially with jiginsertion hole 111. As a jig is inserted into jig insertion hole 111 andis rotated, adjusting gear 109 can be rotated from the outside of uppercase 35.

As upper case 35 and lower case 15 are assembled to each other, asillustrated in FIG. 10, in adjusting gear unit 27, intermediate gear 107meshes with segment gear 67 of lens unit 13 mounted on lower case 15.Therefore, in imaging device 11, as adjusting gear 109 is rotated fromthe outside of upper case 35, lens unit 13 can be rotated.

Adjusting gear 109 can be rotated, for example, by a predetermined angle(for example, 45 degrees) from a reference position. Accordingly, forexample, an image rotation in a range of 90 degrees is possible. Inaddition, the number of teeth of adjusting gear unit 27 is determined,for example, by a resolution per tooth.

FIG. 14A is a perspective view illustrating an example of a state inwhich sub-cover 25 is detached from imaging device 11. FIG. 14B is anenlarged view illustrating an example of the vicinity of blockingportion 117 provided in sub-cover 25. FIG. 15A is a plan viewillustrating an example of a rotation structure of lens unit 13 ofimaging device 11. FIG. 15B is an enlarged view illustrating an exampleof the vicinity of adjusting gear 109 of FIG. 15A.

Adjusting gear 109 is exposed to the outside from adjusting gearpenetration portion 103 of upper case 35. Sub-cover 25 is fixed to uppercase 35. As sub-cover 25 (an example of a cover) is mounted on uppercase 35, sub-cover 25 covers adjusting gear 109 of adjusting gearpenetration portion 103 (see FIG. 1).

Sub-cover 25 has protrusions 113. Protrusions 113 mesh with adjustinggear 109 to restrict the rotation of adjusting gear 109. Protrusions 113are formed, for example, in a shape of a pair of protrusions.Protrusions 113 are formed on the inside of blocking portion 117. InFIG. 14B, the number of protrusions 113 is two, and may also be three ormore.

Annular sub-cover packing 97 (an example of a cover packing) in whichadjusting gear 109 is accommodated is mounted in adjusting gearpenetration portion 103 of upper case 35 on the inside of adjusting gearpenetration portion 103.

In sub-cover 25, cylindrical blocking portion 117 which presses annularend surface 115 of sub-cover packing 97 and air-tightly surroundsadjusting gear 109 is formed. Accordingly, when sub-cover 25 is mountedon upper case 35, a gap between blocking portion 117 of sub-cover 25 andadjusting gear penetration portion 103 is air-tightly sealed bysub-cover packing 97.

Next, the action of imaging device 11 will be described.

FIG. 11A is a perspective view illustrating an example of a state inwhich dome bracket 21 and lens unit 13 are disassembled from each other.FIG. 11B is a perspective view illustrating an example of a state inwhich lens unit 13 abuts dome bracket 21. FIG. 12A is a plan viewillustrating an example of dome bracket 21 abutted by lens unit 13. FIG.12B is a side view of FIG. 12A. FIG. 13 is a sectional view taken alongline 13-13 of FIG. 12B.

In imaging device 11, as illustrated in FIG. 1, dome cover 19 protrudesoutward from case 17 through opening 41 of case 17. The circumferentialedge portion (dome cover flange portion 91) of dome cover 19 isinterposed between top plate portion 33 and dome bracket 21. Asillustrated in FIGS. 11A and 11B, (fitting outer diameter portion 57) oflens unit 13 is fitted into inside opening 65 of dome bracket 21 formedin an annular shape. Accordingly, as illustrated in FIG. 12B, theposition of lens unit 13 is determined to have the same axis as that ofdome bracket 21.

As illustrated in FIG. 13, as stepped portion 69 formed in the outercircumferential portion of lens unit 13 abuts dome bracket 21, themovement of lens unit 13 in a direction approaching dome cover 19 (adirection along the optical axis) is restricted. Lens unit 13 is biasedin a direction approaching dome cover 19 by lens holding spring 23 (seeFIG. 10) provided between lens unit 13 and bottom plate portion 31. Thatis, lens unit 13 is pressed against top plate portion 33 side frombottom plate portion 31 by lens holding spring 23 such that the positionthereof is determined. Therefore, stepped portion 69 is in a state ofabutting dome bracket 21. Accordingly, a tilt of lens unit 13 relativeto dome bracket 21 is restricted.

Lens unit 13 is rotatable relative to opening 41 in a state in whichstepped portion 69 abuts dome bracket 21.

Dome bracket 21 is disposed substantially in parallel to bottom plateportion 31. Lens unit 13 allows stepped portion 69 to abut dome bracket21. Accordingly, in imaging device 11, the position of lens unit 13 isdetermined to be parallel to the case installation surface, and thus thepositional accuracy of dome cover 19 and lens unit 13 can be ensured.

In imaging device 11, when an impact is applied to dome cover 19 fromthe outside of case 17, dome cover 19 is distorted and the impact isalso applied to dome bracket 21. When the impact is applied to domebracket 21, a force that makes lens unit 13 retreat by means of steppedportion 69 is exerted. Therefore, when the impact is applied, lens unit13 retreats in a downward direction (toward bottom plate portion 31side). Accordingly, the impact is reduced before the deformed dome cover19 abuts lens 51 of lens unit 13.

Since the force that makes dome bracket 21 be lowered (in a directiontoward bottom plate portion 31) is exerted, lens unit 13 that abutsstepped portion 69 compresses lens holding spring 23. In a structureaccording to the related art, when a dome cover is distorted, first, thedome cover abuts the lens of a lens unit. Contrary to this, in imagingdevice 11, dome bracket 21 receives the impact and presses a portion oflens unit 13 (stepped portion 69) other than lens 51. Accordingly, whenthe impact is applied to dome cover 19, lens unit 13 retreats via domebracket 21, and thus a direct impact added to lens 51 is reduced. Thatis, imaging device 11 has enhanced vandal proof performance (impactresistance).

In imaging device 11, the lens holding spring 23 is disposed coaxiallywith lens unit 13 and allows lens unit 13 to be biased in a directionalong the axis thereof. Since the lens holding spring 23 has the sameaxis as that of lens unit 13, an impact applied to an arbitrary positionof lens unit 13 in the circumferential direction thereof is equallyabsorbed. In addition, in imaging device 11, since lens holding spring23 is provided coaxially with lens unit 13, the number of lens holdingsprings 23 is one. Accordingly, in imaging device 11, the biasingmechanism of lens unit 13 can be realized with a small number ofcomponents.

In imaging device 11, case 17 has a divided structure including twomembers, that is, lower case 15 and upper case 35. Dome cover 19, innerdome 81, and the like are mounted on upper case 35. Lens unit 13, lensholding spring 23, and the like are mounted on lower case 15. Afterpredetermined assembly members of each of lower case 15 and upper case35 are assembled, lower case 15 and upper case 35 are assembled into onebody. Accordingly, case 17 enables the pre-assembly of lower case 15 andupper case 35.

In imaging device 11, lens unit 13 is held to be movable in a directionapproaching and away from dome cover 19 by lens holder 43. Lens unit 13is biased by lens holding spring 23 in a state of being held by lensholder 43. Lens unit 13 held by lens holder 43 is pressed against domebracket 21 as upper case 35 is assembled. As a result, lens unit 13retreats in a direction in which lens unit 13 compresses lens holdingspring 23. As described above, imaging device 11 can be easily assembledto enter a state in which a pre-load is applied to lens unit 13.

In imaging device 11, the positional relationship between lens unit 13and dome cover 19 is held with high accuracy, and image qualitydeterioration due to positional deviation can be reduced, resulting inan enhancement in the quality of a captured image.

In imaging device 11, dome cover 19 is designed so that the optical paththereof is integrated with that of lens 51, and thus functions as alens. Specifically, it is preferable that the ratio (Tmax-Tmin)/r of thedifference (Tmax-Tmin) between the maximum thickness Tmax and theminimum thickness Tmin of dome cover 19 to the radius r of dome cover 19is 0.75% or higher and 6% or lower. In addition, when the thickness ofdome cover 19 varies, a ghost image is easily generated. Therefore, itis preferable that an anti-reflection coating (AR coating) is applied tothe inner and outer surfaces of dome cover 19. In a case of a imagingdevice which performs panning and tilting, the direction of the lensthereof is changed while the direction of dome cover 19 is not changed.Therefore, image quality deterioration such as defocus occurs. However,imaging device 11 can be configured as an omnidirectional camera whichdoes not need panning and tilting. In this case, dome cover 19 functionsas a portion of a lens and thus high image quality of an image capturedby imaging device 11 can be realized.

In imaging device 11, lens unit 13 having capturing element 63 isrotatable about its optical axis and is provided in accommodation space29 of case 17. Accordingly, since lens unit 13 is configured as anomnidirectional camera, rotation of an image (image rotation) ispossible.

As illustrated in FIG. 15A, lens unit 13 is rotated by adjusting gearunit 27 disposed in accommodation space 29. Adjusting gear unit 27includes adjusting gear 109 for adjusted rotation. As illustrated inFIG. 14A, adjusting gear 109 is exposed to the outside of case 17 fromaccommodation space 29. Adjusting gear 109 exposed to the outside ofcase 17 is covered by sub-cover 25 which is mounted on a portion of case17.

Therefore, as illustrated in FIG. 14A, adjusting gear 109 can be rotatedby detaching sub-cover 25 without opening case 17. Accordingly, theinfiltration of water or dust into accommodation space 29, which mayoccur when case 17 is opened, can be suppressed. In addition, a complexoperation for adjusting and rotating lens unit 13 (for example,disassembly and re-assembly of case 17) can be simplified.

In imaging device 11, image quality may be deteriorated when a capturedimage is rotated during image processing. For this, imaging device 11 isprovided with mechanical adjusting gear unit 27, and thus a capturedimage can be rotated while suppressing image quality deterioration. Lensunit 13 of imaging device 11 may be configured as an omnidirectionalcamera and may not perform rotation in a tilt direction.

In imaging device 11, after lens unit 13 is rotated to a predeterminedposition, sub-cover 25 may be closed. When sub-cover 25 is closed,protrusions 113 provided in sub-cover 25 illustrated in FIG. 14B meshwith adjusting gear 109 and restrict (lock) the rotation of adjustinggear unit 27 as illustrated in FIG. 15B. Accordingly, the rotationalposition of lens unit 13 adjusted to a predetermined position can beprevented from deviating due to vibrations and impacts.

In imaging device 11, when sub-cover 25 is mounted on case 17, adjustinggear 109 is covered by sub-cover 25. Adjusting gear 109 is disposed onthe inside of annular sub-cover packing 97 provided in case 17. Whensub-cover 25 is mounted on case 17, blocking portion 117 of sub-cover 25comes into close contact with annular end surface 115 of sub-coverpacking 97. That is, adjusting gear 109 is sealed by a closed spaceformed by sub-cover packing 97 and blocking portion 117. In imagingdevice 11, the water-proof performance and dust-proof performance ofadjusting gear penetration portion 103 are achieved by a seal structureprovided in the periphery of adjusting gear 109. Therefore, in imagingdevice 11, the closed structure can be reduced in size, and thus a sealmember can also be reduced in size, thereby reducing the probability ofthe infiltration of water or dust.

As described above, according to imaging device 11, the positionaldeviation of lens unit 13 can be prevented, and thus impact resistancethereof can be enhanced. In addition, according to imaging device 11,lens unit 13 can be rotated while the infiltration of foreign matterinto imaging device 11 is suppressed.

This disclosure is not limited to the configuration of theabove-described exemplary embodiment, and any configuration which canachieve the functions described in the appended claims or the functionsof the configuration of this exemplary embodiment can be applied.

In the above-described exemplary embodiment, imaging device 11 which hasboth the positioning structure and the adjusting gear structure isexemplified. However, any one of the positioning structure and theadjusting gear structure may also be omitted.

What is claimed is:
 1. A imaging device comprising: a case whichincludes a bottom plate portion and a top plate portion with anaccommodation space interposed therebetween; a dome cover whichprotrudes outward from the case through an opening formed in the topplate portion; an annular support member which allows a circumferentialedge portion of the dome cover to be interposed between the supportmember and the top plate portion; a lens unit which includes a lens; andan elastic member which is disposed between the bottom plate portion andthe lens unit and allows the lens unit to be biased in a directionapproaching the dome cover, wherein the lens unit includes an outercircumferential portion which is disposed on outside of the lens in adirection along the bottom plate portion and is engaged with an insideopening of the support member, and a stepped portion which is providedin the outer circumferential portion and restricts movement in thedirection approaching the dome cover by abutting the support member. 2.The imaging device according to claim 1, further comprising: a lensholder which is fixed to the bottom plate portion and holds the lensunit via the elastic member, wherein the lens unit includes anengagement member in an end portion on the bottom plate portion side,and the lens holder includes, in an end portion on the top plate portionside, an engagement portion which is engaged with the engagement memberby a biasing force of the elastic member.
 3. The imaging deviceaccording to claim 1, wherein the elastic member is a coil spring whichis disposed coaxially with the lens unit.
 4. The imaging deviceaccording to claim 1, wherein the case includes a first case having thebottom plate portion and a second case having the top plate portion, thedome cover and the support member are provided in the first case, andthe lens unit and the elastic member are provided in the second case. 5.The imaging device according to claim 1, wherein the dome cover isformed so that a ratio of a difference between thicknesses of the domecover to a radius of the dome cover is 0.75% or higher and 6% or lower.